Exact previous verbs.. my solution would also solve the issue of you adding duplicate verbs each time a GM is promoted. Also, you do realize that you're adding those verbs every single time you call that proc, and that it's not doing what it's probably intended to do, right? You're just calling it on the person who invoked it, when you probably should be checking every GM, and IF they don't already have those verbs for whatever reason, add them.
Exact previous verbs.. my solution would also solve the issue of you adding duplicate verbs each time a GM is promoted. Also, you do realize that you're adding those verbs every single time you call that proc, and that it's not doing what it's probably intended to do, right? You're just calling it on the person who invoked it, when you probably should be checking every GM, and IF they don't already have those verbs for whatever reason, add them.